ARM: 7755/1: handle user space mapped pages in flush_kernel_dcache_page

commit 1bc3974 upstream. Commit f8b63c1 made flush_kernel_dcache_page a no-op assuming that the pages it needs to handle are kernel mapped only. However, for example when doing direct I/O, pages with user space mappings may occur. Thus, continue to do lazy flushing if there are no user space mappings. Otherwise, flush the kernel cache lines directly. Signed-off-by: Simon Baatz <[email protected]> Reviewed-by: Catalin Marinas <[email protected]> Signed-off-by: Russell King <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
raspberrypi · Jul 3, 2013 · c5ba85b · c5ba85b
1 parent 1ab7a7e
commit c5ba85b
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Showing 2 changed files with 34 additions and 3 deletions.
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
@@ -320,9 +320,7 @@ static inline void flush_anon_page(struct vm_area_struct *vma,
 }
 
 #define ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
-static inline void flush_kernel_dcache_page(struct page *page)
-{
-}
+extern void flush_kernel_dcache_page(struct page *);
 
 #define flush_dcache_mmap_lock(mapping) \
 	spin_lock_irq(&(mapping)->tree_lock)

diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
@@ -297,6 +297,39 @@ void flush_dcache_page(struct page *page)
 }
 EXPORT_SYMBOL(flush_dcache_page);
 
+/*
+ * Ensure cache coherency for the kernel mapping of this page. We can
+ * assume that the page is pinned via kmap.
+ *
+ * If the page only exists in the page cache and there are no user
+ * space mappings, this is a no-op since the page was already marked
+ * dirty at creation.  Otherwise, we need to flush the dirty kernel
+ * cache lines directly.
+ */
+void flush_kernel_dcache_page(struct page *page)
+{
+	if (cache_is_vivt() || cache_is_vipt_aliasing()) {
+		struct address_space *mapping;
+
+		mapping = page_mapping(page);
+
+		if (!mapping || mapping_mapped(mapping)) {
+			void *addr;
+
+			addr = page_address(page);
+			/*
+			 * kmap_atomic() doesn't set the page virtual
+			 * address for highmem pages, and
+			 * kunmap_atomic() takes care of cache
+			 * flushing already.
+			 */
+			if (!IS_ENABLED(CONFIG_HIGHMEM) || addr)
+				__cpuc_flush_dcache_area(addr, PAGE_SIZE);
+		}
+	}
+}
+EXPORT_SYMBOL(flush_kernel_dcache_page);
+
 /*
  * Flush an anonymous page so that users of get_user_pages()
  * can safely access the data.  The expected sequence is: